Population Ecology

1
Population Ecology

• Chapter 52

2

• Population - group of individuals living in same
  area at same time.
• Population density - of individuals per unit
  area.
• Population dispersion - arrangement of population
  in area.

3
(No Transcript)
4

• Dispersion patterns happen 3 ways.
• 1Clumped dispersion - individuals in groups.
• 2Uniform dispersion individuals evenly spaced
  out.
• 3Random dispersion - individuals live regardless
  of where other individuals live.

5
CLUMPED
6
UNIFORM
7
RANDOM
8

• Demography - study of statistics of a population.
• Life tables - show summary of specific ages of
  population and survival rates.

9
(No Transcript)
10

• Survivorship curve - can see how many individuals
  are alive at specific ages.

11
(No Transcript)
12

• Reproductive tables - reproductive rates at
  various ages.
• Focus only on females and not males in these
  tables.

13
(No Transcript)
14

• Life history - traits that affect organisms
  schedule of reproduction and survival.
• 1Big-bang reproduction (produce large number of
  offspring sometimes followed by the organisms
  death)
• Known as semelparity.

15
The agave plant
16

• 2Repeated reproductive episode - organism
  produces smaller numbers of offspring.
• This is also known as iteroparity.

17

• Change in population - of births minus of
  deaths during that same time.
• Equation ?N/?t r r difference between
  birth and death rates, ?N change in population
  size, and ?t change in time.

18

• Limitations on population growth due to
  resources.
• K carrying capacity.
• Carrying capacity max of individuals an area
  can handle based on resources.

19

• Logistic population growth model - incorporates
  affect of population density on rate of increase.
• Carrying capacity cannot be exceeded - graph is
  S-shaped.

20
Carrying capacity equals change in population
size
21
Carrying capacity
Cannot exceed carrying capacity
22

• Life histories - predict how population will
  reproduce.
• 1K-selection - live and reproduce around K.
• 2r-selection - high rates of reproduction, but
  live in environments where populations are well
  below K.

23

• 2 factors determine the growth of a population.
• 1Density-dependent factors increase their effect
  as density increases (negative feedback)
• 2Density-independent factors - not affected by
  density increase.

24

• Negative feedback - caused by several different
  factors.
• One - resources (force populations to stop
  reproducing if conditions are crowded)

25
As of planted seeds increase, reproducing
decreases
26

• Competition for resources can force decreased
  reproduction rates.
• Need to defend space can reduce population size.
• Predation can decrease the size.

27
(No Transcript)
28

• Human population has been steadily growing since
  1650.
• Zero transition growth of births of deaths.
• Only way to steady out population growth.

29
(No Transcript)
30

• One of the difficulties with population growth is
  looking at the distribution of ages.
• The problem is that the carrying capacity of
  Earth has not been determined.

31
(No Transcript)
32

• http//www.youtube.com/watch?vGECJcW2Ifm4